Read the original writings on quaternions by Sir William Rowan Hamilton. Hamilton was an astronomer and mathematician. He was researching ways of extending complex numbers to higher spatial dimensions. Enter quaternions.
A modern mathematician, David R. Wilkins, has taken Hamilton’s original writings and published them in a single text. Hamilton explained his discovery in 18 articles that were published across several issues of The London, Edinburgh and Dublin Philosophical Magazine and Journal of Science between 1844 through 1850.
I wouldn’t generally include a textbook or materials this old amongst the general sections of The Free Textbook List but it is my understanding that Hamilton’s work is still currently studied by students and therefore still current.
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View this Free Online Material at the source:
On quaternions, or on a new system of imaginaries in algebra.
